<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      body {
        text-align: center;
        color: #666;
      }
      .box {
        margin: 0 auto;
      }
    </style>
    <style>
      /* 在这里完成作业 */
      .box {
        border: 100px solid;
        width: 0;
        height: 0;
        border-color: transparent transparent #579ef8 transparent;
        transform-origin: center 150px;
      }
      .box:hover {
        transform: rotate(0.5turn);
      }
    </style>
  </head>
  <body>
    <div class="box"></div>
    <p>鼠标移动上去试一试</p>
    <p>颜色值：#579ef8</p>
  </body>
</html>

